Garbage Characters Printed on Random Pages (HP LaserJet 4000)

I have a client with a printer. Suddenly the printer has begun printing garbage characters on some of the pages. See the attached image for a part of a page that was printed with garbage characters on it. It is a HP LaserJet 4000 printer, using the PCL 5 downloaded from HP's website. I've tried replacing the printer driver with newer / different ones from HP's website, but have had no luck.

Have you already performed a complete power down?
You didn't mention whether this was a local printer, network printer or if it is on a print server.
If network, and you have a spare JetDirect card, you could swap them out.
If local, try replacing the parrallel cable.

yeah sounds like a hardware glitch to me too. has anything new been brought into the office when the problem started? the other thing it could be is power spikes upsetting either the printer or the pc a power filter might help.

The control sequence is being printed as data (rather than being interpreted) because the printer has 'lost its way' in the print stream, because something in the stream is not in the expected format; i.e. the incoming print stream is corrupt.

If the exact same fault (i.e. same garbage characters at the same place) occurs whern the same document is printed again, with the same driver settings, then this could indicate a driver fault.
However, this is most unlikely.

As SirtenKen and speed_54 have indicated , it is much more likely to be due to random bit corruptions introduced by some sort of hardware glitch.

Check cables, connectors, ports, NICs, routers, switches, etc.
It can sometimes be quite difficult to track down the cause of such random corruptions; use a process of elimination (i.e. replace one component at a time), starting with the easiest and cheapest (cables).

Just a thought..
I am looking at the sample and I see that the image is scanned that they are attemping to print. it can be an issue with the scanner and the image that is being produced by it and not the printer. If this is the case you "should" get the same error every time that you print the same page.
the print is not crooked that the printer is placing (garbage) yet the scanned image is crooked. can you see if they have the scanner on sight. If they do then reboot that check cables look for resorces being hogged when scanning try a different file format etc...

It still can be the printer or hardware as DansDadUK, speed 54,and sirtenken have said.
if looks like it is the printer I would replace the following in this order
1.Network card
2 Firmware dimm
3. Formatter

Manage projects of all sizes how you want. Great for personal to-do lists, project milestones, team priorities and launch plans.
- Combine task lists, docs, spreadsheets, and chat in one
- View and edit from mobile/offline
- Cut down on emails

I just recently resolved this issue. If the printer did not like a certain page, it would print the same garbage characters in the same spot on that page, no matter how many times you printed it.

After much trial and error, I found that the PCL 5 drivers that came with Windows were causing the issue. I switched the drivers to the PCL 6 drivers that came with Windows, and everything worked fine. I'm not sure why the PCL 5 drivers did not work, but I'm glad it has been resolved.

Points to DansDadUK for correctly indicating that it could be a driver issue.

I just recently resolved this issue. If the printer did not like a certain page, it would print the same garbage characters in the same spot on that page, no matter how many times you printed it.

After much trial and error, I found that the PCL 5 drivers that came with Windows were causing the issue. I switched the drivers to the PCL 6 drivers that came with Windows, and everything worked fine. I'm not sure why the PCL 5 drivers did not work, but I'm glad it has been resolved.

Points to DansDadUK for correctly indicating that it could be a driver issue.

If you use a Brother DCP 130C or similar Brother printer, at some point you might encounter the following problem: after you change the ink cartridge, the printer displays an "ink empty" message.
Sometimes you just need to follow the instructions…

This video gives you a great overview about bandwidth monitoring with SNMP and WMI with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg).
If you're looking for how to monitor bandwidth using netflow or packet s…

You have products, that come in variants and want to set different prices for them? Watch this micro tutorial that describes how to configure prices for Magento super attributes.
Assigning simple products to configurable: We assigned simple products…